This invention relates to harvester headers and more particularly to such headers with an improved mechanism for conveying and converging a plurality of rows into a narrow throat of a harvester for crop processing. The invention has particular utility with forage harvesters but may also have application to combines.
Heretofore most forage harvesters operating in row planted, stalk crops such as corn utilized alternatively row crop headers capable of harvesting a maximum of one to three rows at a time. However, currently available forage harvesters have sufficient capacity and power to be capable of harvesting more than three rows at a time. Accordingly, it would be desirable to develop a header capable of harvesting a maximum of four or more rows at a time and retrofitable onto currently available forage harvesters. The width of such harvester cutterheads and the width of the crop receiving throat into the cutterhead chamber is relatively narrow as the width has generally remained the same as new headers have been introduced which are capable of accommodating larger and larger numbers of crop rows at a time. As an example, the width of the crop receiving throat on forage harvesters currently available from Deere & Company and others is about 55 cm. The problem becomes more severe the greater the number of rows the header is designed to accommodate because of the greater number of crop-conveyors--one pair for each row. The conveyors must be laterally spaced at the forward end of the header across the total width of the rows to be harvested and must be converged together at their rear ends in the small area adjacent to the harvester throat. Also, the increased volume of crop material which must be converged together per unit time into the throat increases the difficulty of providing clog-free feeding. For example, when three-row headers were introduced which were capable of being retrofitted on the harvesters used in the past for only two-row headers, a number of solutions were developed as exemplified in U.S. Pat. No. 3,791,117. The patent discloses a header with three pairs of conveyors used to convey and converge, respectively, three individual rows of crop into the narrow harvester throat. The discharge ends of each pair of conveyors are crowded into a relatively narrow discharge zone adjacent the throat and the middle pair of conveyors is spaced above and partially overlaps the outer two pair of conveyors. In addition, the discharge ends of the middle pair of conveyors is spaced slightly forward of the discharge ends of the outer two pairs of conveyors.
In the design of such three-row headers in the design of four-or-more-row headers, the overriding problem is how to position the necessary number of pairs of conveyors in an area slightly forward of and adjacent to the harvester throat so as to provide a positive clog-free feeding of the individual rows of crop material into the harvester throat. It is generally accepted that the closer the discharge ends of the conveyors are positioned to the throat, the higher the probability that efficient, clog-free conveyance of the crop into the throat may be obtained. This is because positive feeding of the crop material in the conveyors can only be obtained up to but not beyond the discharge ends of the conveyors and beyond that the crop material from any one pair of conveyors must be pushed into the throat by crop discharge from that same pair of conveyors or pulled forwardly into the throat with crop being positively fed in adjacent pairs of conveyors.
One approach to the design of a four-row header is shown in U.S. Pat. No. 4,106,270. In this design, the two inner pairs of conveyors are spaced below that of the two outer pairs of conveyors and have their discharge ends spaced forwardly of the crop discharge ends of the two outer pairs of conveyors. Also, each of the two outer pairs of conveyors partially overlap respectively the adjacent one of the inner pairs of conveyors.